Air permeable fire retarding and flame proof partitions, doors and the like



March 27, 1.962 G. RATZEL 3,027,272

AIR PERMEABLE FIRE RETARDING AND FLAME PROOF PARTITIONS, DOORS AND THELIKE Filed Nov. 24, 1958 1 Mfml W/PE INVENTOR 65/70 19725; BY%MAV%ATTORNEYS United States Patent AIR PERMEAELE FIRE RETARDING AND FLAMEPROOF PARTITIONS, DOORS AND THE LIKE Gerri Riitzel, Illertissen,Germany, assignor, by mesne assignments, to Alim Corporation, New York,N.Y., a

corporation of New York Filed Nov. 24, 1958, Ser. No. 775,899 Claimspriority, application Germany Nov. 23, 1957 4 Claims. (Cl. 117-99) withfire retarding chemicals or coated with foam form- .ing fire retardantcompositions to prevent the spread of fires. Such partitions, however,had thedisadvantage that no air could be circulated between the spacesthus partitioned. Also, fire walls or fire doors provided with doublesteel surfaces are rather expensive and also do not permit thecirculation of air.

Previously it has not been possible to prepare larger openings whichespecially serve for ventilation, such as, for example, cable shafts,mine shafts and the like, in such a Way that penetration of firetherethrough could be completely prevented.

According to the invention it was unexpectedly found that fire-retardingand flame proof partitions, doors, windows and the like while normallypermitting a practically undisturbed passage of air therethrough couldbe produced from air permeable carriers, such as fine meshed nettings orgrids of any desirable material, such as, for example, iron wire, orother metals or also of organic materials. According tothe inventionthese carriers are coated with a fire protecting coating which isincombustible and expands or puffs up upon heating. Such coating isapplied to the carrier so that the openings therein serving for passageof air therethrough are not sealed. When such carriers are subjected tothe action of heat the fire retarding coating expands to close theopenings and thusly prevents the penetration of flames therethrough. Inview of its incombustibility and insulation, direct transfer of the heatof the fire is hindered.

Numerous fire retaring compositions suitable for the fire retardingcoating according to the invention have already been developed. Thosewhich essentially consist of a synthetic resin and a foam formingmaterial, and if desired a carbon forming component such as glue orstarch have proved particularly effective. Compositions of this natureare fully described in Jones et al. U.S. Patent Number 2,523,626 as wellas in German Patent 962,824 and U.S. Patent Number 2,881,088 whichcorresponds to such German patent.

Preferably, the fire retarding compositions employed according to theinvention contain about 50 to 80 parts by weight of foam formingmaterial and about 3 to 50 parts by weight of synthetic resin and ifdesired to 50 parts by weight of a carbon forming component.

The first retarding compositions employed according to the invention, inaddition to the compositions indicated above, can also contain diluentsor inert fillers such as asbestos powder, barium sulfate, kieselguhr andthe like.

The following materials can advantageously be employed as the foamforming component of the fire retarding compositions employed accordingto the inven tion: phosphoric acid and its salts such :as monoammomum ordiammonium phosphate, ammonium sulfate, sulfamic acid, ammoniumsulfamate, ammonium bromide, sodium tungstate, sodium borate and boricacid.

The resin component of the fire retarding compositions according to theinvention preferably is a urea-formaldehyde resin and/or aurea-formaldehyde-acrolein resin. Mixtures of 40-60% ofurea-formaldehyde resin with 6040% of urea-formaIdehyde-acrolein resinhave been found particularly suitable. Urea-formaldehyde resins in whichthe proportions of formaldehyde component to urea component is l to 2.5moles of formaldehyde component per mole of urea component areparticularly suited. Urea-formaldehyde-acrolein resins in which theproportions of the components are about 2 to 2.5 moles of formaldehydecomponent and about 0.12 mole of acrolein component per mole of ureacomponent are preferred.

Suitable carbon forming materials which can be used as the carbonforming component of the fire retarding compositions employed accordingto the invention, for example, are as follows: starch, dextrin, gumtragacanth, figur, mannitol glucosamine, glue, casein, gelatin and theli e.

The fire retarding compositions employed according to the invention aregenerally applied to the surfaces of the air permeable carrier as asolution or suspension or emulsified in a liquid medium. Water isgenerally the cheapest suitable material. Drying oil or bituminous paintvehicles or other non-aqueous vehicles may also be employed. The methodof application of fire retarding compositions to the air permeablecarrier can be by dipping, spraying or painting.

Instead of employing nettings or grids as the air permeable carrier,other air permeable structures can be employed, such as, for example,perforated materials in which the small perforation will seal off underthe influence of heat as described above. Also, free hanging curtains ofsingle wires, asbestos fibres and the like can be provided with the fireretarding coating.

The present invention, for example, renders it possible to provide ameans for preventing spread of fire through cable shafts, mine shafts orother openings which cannot be closed off by fire walls or doors becauseof required air circulation, in that the described discontinuoussurfaces which have been provided with a foam forming fire retardingcoating are firmly afiixed transverse to the axis of the shafts oropenings. In order to provide certain effects, it is also possible toprovide a plurality of nettings or girds in series in which theindividual nettings or grids may contain different sized openings whichcan be'staggered with respect to each other and which also may beprovided with fire retarding coatings of different thicknesses.

The novel coated air permeable materials according to the invention canalso be employed as replacements for smaller fire walls. They are verylight and air permeable and are not employed as solid walls. It ispossible to install and dismantle partitions of such materials withouttrouble and without entailing too great an expense. I In addition,surfaces, which, for certain reasons, cannot be painted with fireretardant paints, such as lime walls, can be provided with fireretarding grids or nettings according to the invention. The grids ornettings can also be applied over easily combustible or readily fusiblebuilding elements, such as, for example, foamed styrene plastic, toprovide them with protection against fires.

In the accompanying drawing:

FIG. 1 shows a fire retarding netting according to the invention; and

FIG. 2 shows a cross-section of one of the coated wires of such netting.

In such drawing, 1 represents the carrier netting which,

for example, can be metal Wire or other suitable strand material, suchas asbestos fibre strands and 2 represents the fire retarding coatingover such netting.

The following example will serve to illustrate an air permeable fireretarding structure according to the invention.

Example A netting having square meshes with a mesh opening of 5.5 mm.and formed of iron wire 1 mm. in diameter was coated with an aqueoussuspension containing 200 parts by weight of urea-formaldehyde resin,170 parts by weight of urea-form'aldehyde-acrolein resin, 484 parts byweight monoammonium phosphate, 20 parts by weight of calcium phosphate,76 parts by weight of soluble starch, 50 parts by weight of asbestospowder, all having a particle size passing through a screen of 1,600meshes per cm. The application of the coating was such that upon dryinga coating weighing 900 g. per square meter of netting was obtained.

Such netting, when employed in partitions, doors and the like, normallypermitted good circulation of air therethrough but upon access of fireprevented spread of fire therethrough, as the heat of the fire causedthe coating to foam and swell up to seal off the mesh openings with anincombustible, stable, heat insulating foam.

The urea-formaldehyde resin employed was produced as follows: 35 kg. ofdisodium phosphate were dissolved in 812 kg. of 30% formaldehyde (243kg. formaldehyde) with adjustment of the pH to 8.2 and 243 kg. of ureawere added to such solution. The resulting mixture was stirred for about4-5 hours while maintaining a temperature up to about 40 C. and thenallowed to stand over night. The resulting thick mass was then heated toabout 55 C. and the water content thereof reduced to 510% under a vacuumof 80-100 mm. Hg. As the water evaporates, the temperature is graduallyraised to about 120 C. The resulting semi-dried product was then putinto aluminium pans which were placed in a drying oven maintained at 103C. under a vacuum of 100 mm. Hg. for 24 hours. The originally tough massrose similarly to a cake dough and a coarsely porous frangible productresulted which was easy to remove from the pans and grind.

The urea-formaldehyde-acrolein employed was produced as follows: 17.76kg. of urea, 4.43 liters of distilled water and 0.30 kg. of glacialacetic acid were 'mixed and heated to 50 C. Upon reaching thistemperature, 2 kg. of acrolein were added over a period of 5-6 minutesat a rate that the temperature of the mixture did not exceed 58 C. Afterthe acrolein had been added, the mixture was heated to 70 C. for 30minutes and then cooled to 45 C. The product obtained was a yellowishthinly viscous precondensate.

At the same time, 55.43 kg. of 30% formaldehyde, 4.35 kg. ofhexamethylene tetramine and 15.55 liters of distilled water were mixedin another vessel and the resulting solution mixed with theprecondensate after it had been cooled to 45 C. The resulting mixturewas heated in 10 minutes to C. and maintained at this temperature for 30minutes and then cooled to 20 C. and the pH adjusted with NaOH to 7.2.

Similar results were also obtained when other foam forming fireretarding coating compositions, such as described in Schulenburg US.Patent Number 2,881,088, were employed. Of course, in each instance caremust be taken that the quantity of fire retarding coating applied issufiicient so that upon swelling upon access to fire the openings in thenormally air permeable carrier will be closed.

I claim:

1. An air permeable fire retardant and flame proof fire shieldingelement comprising an air permeable wire netting having spaced openingscoated with an incombustible fire retardant composition which swellsupon heating normally leaving air permeable openings in such shieldingelement but swelling to seal such openings upon access of heat from afire to such element.

2. An air permeable fire retardant and flame proof fire shieldingelement comprising an air permeable carrier provided with spacedopenings coated with an incombustible fire retardant compositioncontaining a foam forming component and a synthetic resin componentwhich swells upon heating normally leaving air permeable openings insuch shielding element but swelling to seal such openings upon access ofheat from a fire to such element.

'3. A fire shielding element according to claim 2 in which saidsynthetic resin component comprises a urea-formaldehyde resin.

4. A fire shielding element according to claim 2 in which said syntheticresin component comprises a ureaformaldehyde resin and aurea-formaldehyde-acrolein resin.

References Cited in the file of this patent UNITED STATES PATENTS391,237 Garrison Oct. 16, 1888 1,497,167 Emerson June 10, 1924 1,985,771Eichengrum Dec. 25, 1934 2,172,698 Clayton et al. Sept. 12, 19392,328,057 Coulter Aug. 31, 1943 2,648,641 Rob'ison Oct. 11, 19532,681,326 Christianson July 15, 1954 2,755,260 Stilbert et a1. July 17,1956 2,881,088 Schulenburg Apr. 7, 1959

1. AN AIR PERMEABLE FIRE RETARDANT AND FLAME PROOF FIRE SHIELDINGELEMENT COMPRISING AN AIR PERMEABLE WIRE NETTING HAVING SPACED OPENINGSCOATED WITH AN INCOMBUSTIBLE FIRE RETARDANT COMPOSITION WHICH SWELLSUPON HEATING NORMALLY LEAVING AIR PERMEABLE OPENINGS IN SUCH SHIELDINGELEMENT BUT SWELLING TO SEAL SUCH OEPNINGS UPON ACESS OF HEAT FROM AFIRE TO SUCH ELEMENT.